Method of making ignition apparatus



July 26, 1949. T. ToGNoLA METHOD MAKING IGNITION APPARATUS Filed Aug. 28, 1942 Y R M m 2 .T i

EVHC'I/HTE :Avi im F'lGl FICE.5.

Patented July 26, 1949 En s TAT es rArnNT oFF-ice METHQD; OFMAUNG IGNI'IBIQN `A111?ARA-'EUS rrqgnoia, Sidney, N. rnsassignorltofnendix Aviation Corporation, South lBend, Imil.f,ra cor- -poraton o'f'Dlaware .ApplicationAug-nst 28, 19412,- seiiial'No' (Cl18-Y- 59) 14 'Claims .invention vvrelates Ato methods for making electrical. structures .impregnated-with insulating material. i

The desirability of =lling .the casingsfof ignition-coils and the l like .with suitable insulating materials `and Vat the same time thoroughly f impregnating ,the Vcontents vof the casing `with said materialslhas long been :recognized .but no satis- 'factory method .of accomplishing the lling .in a satisfactory manner fwith fa. satisfactory-materia1 has zheretofore'. been found. .With .processes .and materials "heretofore practiced Y and used it has not' beerrpossble torcompletel-y fillthe. device with a suitable drysubstance which; has Jthe necessary electrical, heat `resisting -and mosturarepellant `qualities.

It'isaccorfdingly oneroithe objects of .the .present .inventiontoprovidea novel methodiormaking ignition apparatus, ,such as .ignition c oils. and shielding; harnesses, wherein lthe `wires fory carrying electrical current areencased Y.and embedded inan v'insulating, .materiaL Another object of'jthe invention isitoprovide a'noyell method for "filling and impregnating ignition equipment vwith an insulating material consisting chiefly of processed ,oil ,obtained from theshells .of Cashew nuts or substances having similarproperties whensuitablyprocessed.

:A further object is toproride a novel y method offmaking filled or impregnatedlignitionapparatus'wherein'theiiling or impregnating vmaterial Atconsists ofa iiquidadaptedtodry through chemi- Vrilal reaction'with orwithoutthe application.. of f eat.

"The above and'further objects aridmoyel fea- .l

tures of "theinvention Vwill more fi'illy appear fromthe followlngfdetaile'd description whentthe same isread4 in connection `with .the accompanying drawings. ItListo be lexpressly understood,

I'h oweven'that `the 'drawings areifor the ,purpose f illustration only and arenot Iintended ..tode "neith'lirnits of' the invention, reference. forthis Ihitter'rpurpose l-being hadlxprimarily .to Lthe Aapperidedclaims.

"In thedrawings, wherini-Iike referencezchardi5 actersrfer" to,l like Hparts throughoutthe several views,

Figlie a side elevation,;partly. in sectionaand withparts; broken away, `.ot .oneiype of., apparatus 'which may be employed .in 4,earryingout the 50 process idf .the invention;

T ig. 2 is ',a c sectional view of .said :apparatus takenlsubstantially-on Enel-s2 ,.ofgFig. 1,1;and

lliguretls ,aidetail sectionshowingtthe. shrinkage'reservoirj in `linlacenanrlj full.

The ,novehprocess comprehended ffby the xinvention is` described gbelow, `by way of example, -intiis' applicationlto.ftheimpregnation .ofignition *coils andi the simultaneous: filling. .of-the casi-rigs which been vfound :to be particularly suitable for ,lling fcoils .and radio-shielding harnesses consistent -a product resulting from the processingfof:thefcaslsiewnut shell oil in accordance with/U. S.patents issued to The I-IarVel Corporation, .such aas Harvey 4Patents Nos. 1,725,797, Plaow and 128,247 vA mung .material 4thus constituted isstableand durable and has excellent heat resisting a and insulating properties, as well as being ,yieldable and hence i not subj ect to v cracking under -Vibration .or shock.

QQne suitable apparatus adapted for use lin carrying putthe -lniethodnof the invention and particularly ,adapted, forlling and impregnating an .ignition coil ...5 shown iin ,the drawings, `by .way, ofexaniple. iThecoilmay beef any suitable design, the one shown comprising a laminated metallic coresln whichprimary and secondary Windingsl fand ,are wound. The windings .and the centralrportion of .coretareenclosedin a casing ,which,`as illustrated, comprises -a shell 9 of,moldedinsulatingmateral and end walls or lplatestll andtl yonsiniilar -material surrounding .the .proieotingendsbf ,core.v6. .Thecoil casing is prefer-ably vrenderedsubstantially. air-,tight o by .use of lacquer, wax, ,or other. suitable substances at .the innerand.puterl peripheries of end .plates I9-a11d..l,l,.if .these areinot integralwith shell `9. The walls .1. 0 and il are .provided Vwith `small ,openings .1.2 ,an d',.l.3, respectively, .thef former serving aaaninlet fzorrthelling. compound andthe Alatterasa` bleednole forair and the lling compound. ,These openings I2 and I3 arepreferably located as far lawaylfromone another as isprac- .ticallymossible .in..order to insure a thorough limpregnationpfthe. coil windings as'the lling Comparinifinds. its.wayfrom the inlet i2 to the .vbleedfhole The mechanism shown for lling coil f5 'com- 3 prises astationary support .or member I4 mounted Lonaoizaloleuor. bench in any suitable manner (not rShOwn). Attached tothe-bottom face :ofmem- .benlhbyv boltsi. 5.is,.a, plate lI 6 vwhich. has a `gasket `,L7.otrnbber another -suitable ymaterial, counter- 4sunleintigre periphery-,thereof and held.v in place 4byeJ bracketft. :Suspendediromplate lois a rigid supporting cradlefconsisting `of-twostraps L9, Whichaarasecuredto .thelplate by bolts -2ll, .andra rcrossgpi-ece `2 lqsecuredito the lower ends `of straps. i9.

.,Cradle.t9,.2l serves asv anwunting-` for suitable snpportingrapparatus for. coil;.5;whereby. the latter maybe. raisedfiand, lowe-redinto 1 and: out of contaetwith ansadapterplate 22 to be hereinafter 55 `described. Q Said .-,supporting apparatus in the formsshowng consists .off a-.block f23 having abore tor ssilidably receivling a spindle t- 24. The .upper Y,portion-mf :thelatter1r is threaded :and has a nut 15!threadedi;thereonwloicr1 -res1zs. aipon7 the; upper "therefor withdnslatingmaterial. `Onerxnater-ial surface 'of block 23 and may be turned gin-opposite directions by means of suitable handles 26 to eiect a raising and lowering of spindle 24. The latter is prevented from turning by a pin 2l, which is mounted in block 23 and extends into a longitudinal slot 28 in spindle 24. On the upper end of said spindle there is preferably mounted a tray 29 for catching any lling material that flows out of coil casing 9 through bleed hole I3, said tray being held against rotary movement, if desired, by a pin and slot connection 30, 3| with spindle 24.

Loosely mounted on tray 29 is an adapter assembly which may be varied to suit the particular type of coil or other unit being lled. In the form shown, said assembly comprises a member 32 which is centered by the reduced upper portion of spindle 24 and rests upon the central portion of tray 29. A plate 33, which engages the lower face or end of coil 5, is resiliently supported on member 32 by a plurality of springs 34, of i which there are preferably four, that surround guide pins 35 which are attached to plate 33 and slidably extend through passages in member 32.

The specific structure of plate 33 will depend upon the particular coil or other unit for which it is adapted. As shown, adapter plate 33 is provided with a passage 36 for receiving the lower end of coil core 6. It is also provided with a groove 31 at the periphery of plate 33 (Fig. 1) for the purpose of clearing bleed opening I3 to permit air and filling compound to flow out through the latter.

Mounted on the lower face of plate I6 directly above coil 5 is the upper adapter plate 22, the

construction of which also depends upon the i contour of the device being filled with insulating compound. As shown, plate 22 is countersunk for receiving the end of core 6 and is provided with a slot 38 in the upper surface thereof for directing the lling compound. Slot 39 is con- -1 nected at one end with a passage 39 leading to inlet opening I 2 and at its other end to a central threaded opening 40 in plate I6. A supply container 4| for filling compound 42 is provided at its lower end with a threaded extension or nipple threaded into opening 40. The compound will thus ow through outlet 43 in the bottom of the container, through slot 38 and passage 39 into the coil casing through opening I2. If desired, a gasket 44 of cork or other suitable material may be interposed between the upper face of coil 5 and adapter plate 22 to render the contact between coil 5 and plate 22 substantially air and liquid tight.

Container 4I is fitted with a valve 45 for opening and closing outlet 43. Valve stem 46 is guided at its lower end by a bracket 4I and has external threads at the upper end thereof which cooperate with internal threads on a bracket 48. Handles 49 may be xed to the upper end of stem 46 for the purpose of turning it to thereby move valve to closed or open position.

Coil 5 and its supporting structure may be enclosed by a removable jar 5Il which is preferably made of glass. The upper edge of jar 59 ts against gasket Il (Fig. 2). The air may be exhausted from said jar and, hence, from the interior of coil 5 by means of a conduit 5| which is iixed in an opening in plate I6 and connected through a valve 52 with a suitable source of vacuum, such as a suction pump (not shown). The interior of jar may also be connected with atmosphere through a small bleed hole 53 in the end of a pipe through which flow is controlled by a valve 54.

A suitable pressure gauge 55 may be provided for indicating the pressure within jar 5 9 and a support or pad 5,6 may be suitably hinged or otherwise suitably supported so that it may be swung beneath jar 50 to obviate dropping and breaking of the latter if the vacuum within the jar should fail. The detailed operation of the above-described apparatus will appear from the following description of the novel process comprehended by the invention.

In carrying out the process of the invention as applied to coil 5, the primary and secondary windings 1, 8 of the coil are wound on core 6 and then thoroughly dried in a Vacuum oven. The winding and core assembly is then placed in casing 9, I0 and cover II is put in place. The other end I0 of the casing may be integral with shell 9 or, if it is not, it may be installed in the same manner as cover I I. The outer rim of cover I I is coated, before it is inserted in shell 9, with a sealing substance, such as tacky Bakelite varnish or lacquer to hold the same in place and render the joint substantially air-tight. In addition, varnish or some other sealing substance may be placed on the joint after the cover is in place. Any spaces between core 6 and the peripheries of the openings in the ends I9, I I of the coil casing and any openings for electrical leads or the like may be sealed with valspar putty or a similar sealing substance. The encased coil is then dried again in a vacuum oven, after which it is ready for lling with the insulating compound 42.

One compound which has been successfully used in carrying out the process comprises a mixture of processed cashew nut shell oil and paraformaldehyde, formaldehyde, or a similar reaction agent. In preparing this compound or mixture, three parts by weight of powdered paraformaldehyde are slowly added to and simultaneously thoroughly mixed with parts by weight of processed cashew nut shell oil, such as that known commercially as Harvel No. 621 made by Irvington Varnish and Insulator Company, Irvington, New Jersey, said processed oil having a viscosity, at 75 to 80 F., of about that of heavy liquid lubricating oil. After these ingredients have been thoroughly mixed in an open top container, the latter with the mixture therein is placed under a high vacuum in a bell jar or the like and the mixture is stirred vigorously for several minutes. After stopping the mixer or agitator, the filling mixture is submitted to atmospheric pressure again. This vigorous mixing or stirring under vacuum should be repeated one or more times for the purpose of removing substantially all air and gases from the mixture.

When substantially all of the gases have been removed from the mixture in the above manner, it is placed in container 4| while valve 45 is in closed position. With the coil held rmly between adapter plates 22 and 33 in the manner shown in the drawings and after a high vacuum (preferably 28 to 30 inches) has been established in jar 50 by opening valve 52, the valve 45 is moved to open position by turning stem 46 with handle 49. The compound 42 is then forced from the container by atmospheric pressure into the evacuated coil casing through inlet opening I2 and fills all of the voids therein, some finally reaching and flowing out through bleed port I3.

After a small amount of the filling compound 42 has come out through bleed port I3 and such ow is smooth and continuous, thereby indicating that the coil casing is completely filled and the coil windings are impregnated with the compound,

.the waive 12 is --closed xandfatmospherie vyaiye .ll'is-openedftorermit the entr-ance Ofieir 'through epening. The-latter preferably very smallrse. that the .changefreni, full vacuum teatniospheriepressure Within-jar ilrtakestplace slow,- ueeess has beenhadby employing an latmesphericbleed port ,.53 V.of suclnsize that it r-en quires from faboutthirty seconds to 'av-munite Jfor the -cemelete .pressure change. The vpressure change-shou-ldfbe sufciently-slow .to preventany backing up of the liquid filling compoundtin-fthe ceil-reasingfdne to :thc-pressure at bleedjp'ort 13. Aiterzatmospheric pressure has lbeenrestored in jarii, as indicated-by gauge 5.5, thejar is removed and .adapter plate .33 is .lowered vavvayfrom coil .-b'y turning nut 25 Vwhile .theCoil-ismanuallyrheld bythe operator vagainst adapter plate -27/2. The coil should .be drawn away from the latter. plate at :the same time that Val-ve @Sis-moved toward closed position, The valve is constructed in such amanner-as to serve during the closing movement thereof as agplunger for forcing filling compound 4:2 towardthe-ccil and out through hole |23, thereby preventing any of the'com'pound from being pulled outro-:the coilcasing through opening i2 due to its-viscosity and preventing the entrance of any .air .through hole 13.

immediately after removal .of the coilin this manner, 'a cover,suchas adhesive tape, isplaced over .opening -13 and a small hollow cylinder 9B ,oi-,any suitable material, which serves as a resern Voir, is placedon-end .on the enzlle .of the casing arcuridopening i2 and filled vwith some of the `lil-ling,.compound ft2. Ii therehave been any .bubolesinfthe lling material Within the casing, this additional compound .Will'be drawn into the `coil casing-when the .bubbles contract .after removal iv the-.coil from'the vacuumcha-mber or when any settlingof. the compound occurs for any other reason.

The lled coil is then preferably placedsinan ovenlandbakedf-.or theA purpose of speeding up the chemical setting of the liquid compound 42. Suitable baking' for a coil ofthe-typeillustrated in the drawings may. reduire approximately. 15. hours at 120 F. and then 4 hours at 200 F. ,'Ehetmfes and temperatures may differ for diierent size and types of `-ul-leol units. "-In the filling of radioshielding harnesses and other devices Whichfdi-ffer considerably-in shape from coil 5it is necessary lto-.eunployapparatus which diners considerably in .designvfromthe apparatus illustrated but the. fundamentalrnethod employed is the same.-

fhereis .thusprovded a novel vmethod for making ignitiorndevices, suchA ascoils, radiofshielding harnesses-etc., which are-iilled after ,complete assembly with insulating material whichv maybe iniectedinto the same in liquid. form and which sets without-appreciable shrinkage'to a dry, yieldable solidrzthat is not aiected'by high temperatures or moisture and has good insulating properties, The .invention also comprehends a novel method for A`filling such devicesA whereby theouter surface ofthe device is not contaminatedfin `any may with-the filling material.

-Althoughthe method of this inventionv has .been described-in its applicatiQnto the llingofeencased ignitionc9115, it is to.be..expressly understood that the-invention is not'limited thereto. It will-aise be understcodithatthe process. of the inyentionmay be carried 'out withA apparatus other theyspeeic apparatus villustrated .-in the drawings. Other variations which will now be apparent to those skilled in the art may also be made in the specific details of the method and aupa-faune des@ribed L withoutdeparting :iron-1 tine sniritand-,scope-effthe-invention. foriadenition @i .the urnits :ni the Vinvention, reference .primarily ato A. .the appended claims.

Whatis claimed fi, 'rhermethodof :vacuum illinesandimpreg gan:ienitondeviceofatheztypehavingazsub stantially fluid-,tight casing except for .one lor more: llingfholesandrcnefor'morebleedzholesradf geen he l opposite ends :thereof which .method consistsrilplacing said/:ceasing in a chamber with the interorfof the casing. in 'communication with the harlbelfY threughableedhole, evacuating said `eliameer 7and cas-ng, subjecting a liquid .nlling compound to a stirring action under vacuumto removefsubstantially all' free gases therefrom, ernploying ithe vacuum vin said chamber to .inject saidg-assree-compcund through a filling hoie'into Said easinguntilsaid compound flows-from said bleed-hole, slowly admitting :air Vtothe chamber to gradually .reestablish atmospheric -pressure therein, and .subjecting ythe lled ycasing to heat to accelerate the setting of said compound.

l2. Themethod oiiiingand impregnatng ignition apparatus withan insulating compound,` said apparatus 'being cil the type `havingsa casingwlrich isfsubstantially f duid-tight .except for .fill-ing and outlet openings therein, Vsaid illing and outlet nings; being remotely. spaced .from -zeach other, which inciude-f the steps. of. placing said casing lin ,a-,chamberwith the interior of the casing in :com-- inunieation with said'ehaniber lthrough saidsoutietrcpening, evacuating said. chamber and-casing, subjecting a liquid filling compound to stirring action .underavacuum Ato remove lsubstantiallyall ireefgases therefrom, injecting said compound into said.casingthroughqsaid filling opening-until thecasing .is yfilled, and .slowly admitting air to said; chamber :for 'gradually reestablishing atmospheric ,pressure :therein Thefmethod-Lofr insulating ignition apparatus and thelike with .a liquidcompound, saidfappara- .tus aseingof the typ-el'having a-casing -which'is substantially fluid-tight except for lling-an'd'outlot .openings-therein said llingandnutlet openingsheingfremotely spaced froml eachv other, Which eonsistsiinsplacing said casing in a chamber with the inter-ierl of the casing in communication with saidr Vchaining-1rthrough said outlet openingevacuating said-chamber and casing, subjectinga quantityjoffprocessed vcashevvenut-shell*.oil to a stirringwaction while vslowly adding thereto -aporv.- dered drying agent, such .as paraformaldehyde, subjectingthe resultingmixture to a stirring action in anevacuated space, injecting `said compound lrltorsaidcasing .through saidiilling openinguntil' the` casing. is, illed, andv slowly .admitting air .tosaid vcham-ber for `gradually reestablishing atmospheric-pressure therein.

A.V .-Thejzmethod .off insulating ignition apparatus of thestype; having Va -casing which encloses. electif-ical conductors, which includes the steps vof evacuatingtheinterior of said casing, subjecting ailiauidinsulating compound to a stirring actionunder vacuumfor removing substantially all reegases therefrom, injecting said l.compound into the interior .of saidv evacuated casing to -comletelyll'theilatter vand heating thecasing to .soldiythe compound. Y

.f .5. The method. of insulating `ignition vapparatus offvthetype 'havinga casingrfor enclosing-'electrical conducting means, which consistsf'inv-subjecting a flowable insulating substance to a stirring action under vacuum for removing substane .tially all free gases therefrom, evacuating said casing through an opening in one side thereof, and injecting said substance into said casing through an opening in the other side thereof until said casing is filled with said substance.

6. In the method of insulating ignition apparatus of the type comprising a casing, the steps of subjecting a liquid filling compound to stirring action under vacuum to remove substantially all the free gases therefrom, placing said casing in a closed chamber and evacuating said chamber and casing, injecting said compound into said casing through an opening in the wall thereof, and slowly subjecting the casing to atmospheric pressure.

7. In the method of insulating ignition apparatus of the type having a casing, the steps of removing free gases from a liquid substance having a relatively high viscosity, evacuating said casing, injecting said liquid into said evacuated casing through an opening in the wall of the latter, and slowly subjecting the casing to atmospheric pressure.

8. In the method of insulating ignition apparatus of the type having a casing, the steps of removing free gases from a liquid substance having a relatively high viscosity, injecting said liquid into said evacuated casing through an opening in the Wall of the latter, gradually reestablishing atmospheric pressure in said casing, and

thereafter placing a reservoir of said substance in communication with said filling opening while the liquid substance settles and sets in said casing.

9. In the method of insulating ignition apparatus of the type having a casing, the steps of stirring a quantity of polymerized Cashew-nutshell oil while slowly adding thereto a drying agent, such as paraformaldehyde, removing substantially all free gases from said mixture, injecting said gas-free mixture into the evacuated casing for filling the voids in the latter, and slowly subjecting the casing to atmospheric pressure.

10. A method for insulating an ignition device of the type having conductors mounted within a substantially air-tight casing having a filling aperture in one end and a bleed hole in the opposite end thereof, which consists in positioning the casing within a removable container, evacuating the container and casing, introducing through the inlet opening of the casing a liquid insulator from which free gases have been removed, slowly subjecting the casing to atmospheric pressure and baking the casing to accelerate the setting of the liquid insulator.

11. A method for insulating an ignition device of the type having electrical conductors enclosed in a substantially air-tight casing provided with an inlet opening in one end and a bleed opening in the other end, which consists in simultaneously agitating and subjecting a liquid insulator to a vacuum to remove free gases therefrom, introducing the gas-free insulator through the inlet opening by vacuum effective at the outlet opening, slowly subjecting the casing to atmospheric pressure, and heating the casing to accelerate the solidiiication of the liquid insulator.

12. The method of lling and impregnating ignition apparatus with an insulating compound, said apparatus being of the type having a casing which is substantially iiuid tight except for lling and outlet openings therein, said lling and outlet openings being remotely spaced from each other, which includes the steps of placing said casing in a chamber with the interior of the casing in communication with said chamber through said outlet opening, injecting a liquid iilling compound from which substantially all free gases have been removed into said casing through said lling opening until the casing is iilled, and slowly admitting air to said chamber for. gradually reestablishing atmospheric pressure therein.

13. The method of insulating ignition apparatus and the like with a liquid compound, said apparatus being of the type having a casing which is substantially uid tight except for lling and outlet openings therein, said lling and outlet openings being remotely spaced from each other, which comprises the steps of placing said casing in a chamber with the interior of the casing in communication with said chamber through said outlet opening, evacuating said chamber and casing, injecting a liquid compound into said casing through said filling opening until the casing is filled, said compound comprising a mixture of processed Cashew-nut-shell oil and a powdered drying agent, such as paraformaldehyde, from which substantially all free gases have been removed, and slowly admitting air to said chamber for gradually reestablishing atmospheric pressure therein after said casing is lled.

14. The method of setting an encased magneto coil ina resilient solid that comprises stirring Cashew nut shell oil under vacuum whereby to remove therefrom entrapped gases, evacuating the encased magneto coil and impregnating it with a composition comprising the degassed oil and formaldehyde under conditions that tend to maintain the vacuum and exclude gases, setting theoil about the coil by heat, and supplying additional oil to compensate for volume change during setting.

' TULLIO TOGNOLA.

REFERENCES CITED The following referenlces are of record in the iile of this patent:

K Y UNITED STATES PATENTS Number Name Date 483,397 Smith Sept. 27, 1892 518,946 Forbes May l, 1894 627,398 Dolley et a1 June 30, 1899 691,675 Thomson Jan. 21, 1902 917,018 Dempster Apr. 6, 1909 1,037,824 Fasting Sept. 3, 1912 1,242,873 Schroeder Oct. 9, 1917 Y1,270,969 Parker July 2, 1918 1,754,003 Johnson et al Apr. 8, 1930 1,838,077 Harvey Dec. 22, 1931 2,047,260 Franklin July 14, 1936 2,047,273 Kopinski July 14, 1936 2,091,234 Branson Aug. 24, 1937 2,136,423 Fields et al Nov. 15, 1938 2,142,270 Henst Jan. 3, 1939 2,166,205 Anderson et al July 18, 1939 2,183,763 Brown Dec. 19, 1939 2,300,910 Camilli Nov. 3, 1942 FOREIGN PATENTS Number Country Date 389,236 Great Britain Mar. 16, 1933 v410,807 Great Britain May 22, 1934 

